Regarding techniques relating to storage systems, for example, there is a storage virtualization technique for gathering one or more storage areas belonging to a plurality of storage apparatuses, forming and virtualizing them into one storage area, and providing the virtualized storage area to a host computer.
There is also a server virtualization technique for dividing one physical server into a plurality of virtual machines, allocating computer resources, such as a CPU (Central Processing Unit) and memory for the physical server, to each virtual machine, and having each virtual machine execute an OS (Operating System) and applications.
With the storage system using the server virtualization technique, a virtual machine may be sometimes relocated by migrating the virtual machine between different physical servers. For example, Patent Literature 1 describes that when migrating a virtual machine between different physical servers, the virtual machine is migrated in consideration of input to or output from an array group in the virtual machine after the migration.